Smoke filter

ABSTRACT

A smoke filter is provided which is adapted to be affixed to one end of a tobacco rod. The smoke upon passing through the filter attains a very high velocity whereupon it impinges against a curved surface causing liquid and/or solid particles entrained in the high-velocity smoke to be deposited upon the impinged surface. The smoke, subsequent to impingement, follows a curved path prior to being discharged from the downstream end of the filter.

United States Patent Inventor John D, Woods Winston-Salem, N.C. Appl. No. 9,515 Filed Feb. 9, 1970 Patented Oct. 12, 1971 Assignee R. J. Reynolds Tobacco Company Winston-Salem, N.C.

SMOKE FILTER 6 Claims, 4 Drawing Figs.

U.S.Cl 131/10.5, 131/201, 131/210, 131/212 A Int. Cl A24d 01/04, A241 01/08, A24fW/16 Field of Search 131/10.5,

1 Ma /0 Z! [56] References Cited UNITED STATES PATENTS 3,472,238 10/1969 Blount et al. 131/201 X 3,366,123 1/1968 Brothers 13l/lO.5 3,359,988 12/1967 Thomson 131/261 BUX 1,594,606 8/1926 Clivio 131/261 B UX 1,261,038 4/1918 Labreche 131/210 Primary Examiner-Samuel Koren Assistant ExaminerJ. F. Pitrelli AttorneyPendleton, Neuman, Williams & Anderson ABSTRACT: A smoke filter is provided which is adapted to be affixed to one end of a tobacco rod. The smoke upon passing through the filter attains a very high velocity whereupon it impinges against a curved surface causing liquid and/or solid particles entrained in the high-velocity smoke to be deposited upon the impinged surface. The smoke, subsequent to impingement, follows a curved path prior to being discharged from the downstream end of the filter.

PATENTED [1m 1 219m M /U H SMOKE FILTER BACKGROUND OF THE INVENTION Various types of filters have heretofore been proposed for use with tobacco rods such as cigarettes or the like. Such filters, however, because of various design features are beset with one or more of the following shortcomings: (a) the filter embodies a plurality of component parts which materially increase the cost thereof and render same difficult to assemble; (b) the filter is ineffective in removing liquid and/or solid particles from the circulating smoke; (c) an inordinately high pressure drop is produced across the filter causing discomfort to the smoker; and (d) the filter is not readily capable of being assembled by automatic equipment, the functionand opera.

tion of which is well known in the cigarette-making art.

SUMMARY OF THE INVENTION Thus, it is an object of this invention to provide a smoke filter which avoids the aforenoted shortcomings besetting prior filter constructions.

It is a further object of this invention to provide a smoke filter which is adapted to be used with tobacco rods varying in size and length, as well as with various other products such as cigars, pipe stems, etc.

It is a further object of this invention to p ovide asmoke filter the production rate of which is substantially commensurate with the production rate of the tobacco rod to which it is affixed.

Further and additional objects will appear from the description, accompanying drawings and appended claims.

In accordance with one embodiment of the invention a smoke filter is provided which is adapted to be affixed to one end of a tobacco rod. The filter includes an elongated core piece formed of a smoke impervious material. The core piece is provided with an enlarged upstream end'portion disposed in abutting relation with the tobacco rod end, an elongatedv center portion having the exterior surface thereof recessed from the periphery of the upstream end portion, and an enlarged downstream end portion. Snugly encompassing the core piece is a first sleeve of thinperforated material. Portions of the sleeve are spaced from and cooperate with the exterior of the core piece center portion to form an elongated substantially annular first passageway. Another portion of the sleeve cooperates with a peripheral slot provided in the downstream end portion of the core piece so as to form a discharge port communicating with the first passageway. Encompassing the first sleeve is a second sleeve which is spaced therefrom so as to form a second annular passageway. The second passageway communicates directly with the tobacco rod and also communicates with the first passageway .only through a plurality of perforations which are formed in the first sleeve. The smoke upon passing through the perforations attains a very high velocity whereby the high-velocity smoke in the form of jets impinge against the exterior surface of the core piece center portion causing liquid and/or solid particles entrained in the impinging jets to be deposited on said exterior surface. Subsequent to the impingement, the smoke follows a curved path before passing through the discharge port. The discharge port is angularly offset a substantial amount from the sleeve perforations.

DESCRIPTION For a more complete understanding of the invention reference should be made to the drawings wherein:

FIG. 1 is an enlarged fragmentary, longitudinal sectional view of one form of the improved filter shown affixed to one end of a tobacco rod.

FIG. 2 is a perspective view of the upstream end of the filte shown in FIG. 1.

FIG. 3 is a sectional view taken along line 3-3 of FIG. 1.

FIG. 4 is a longitudinal sectional view of an elongated rodlike member formed of a plurality of core pieces arranged in integral tandem relation; said rodlike member being shown snugly encompassed by a first sleeve member.

Referring now to the drawings andmore particularly to FIGS. 1 and 2, an improved smoke filter 10 is shown affixed to one end of a tobacco rod. 11. The rod 11 is of conventional design and includes a core 12 formed of compacted shreds of blended tobacco, and an outer wrapper 13 of thin white cigarette paper. While the improved filter will be hereinafter described with respect to a cigarette rod, it is to be understood, of course, that said filter may be utilized with cigars, pipe stems, or the like. The lengthand size of the rod to which the improved filter is affixed may vary as desired.

The filter 10 is of an extremely simple design and embodies a minimal number of-component parts, such as an elongated smoke impervious core piece 14, an inner or first sleeve 15, an outer or second sleeve 16, and a spacer piece 17 disposed intermediate said sleeves and adapted to maintain same in a predetermined spaced relation.

The core piece 14 is preferably formed of a foam plastic material by extrusion coupled with after forming. In the illustrated embodiment, the piece 14 includes an enlarged cylindrical upstream'end portion 14A, an elongated center portion 14b, which is preferably semicylindrical in configuration, and an enlarged cylindrical downstream end portion He. The upstream end portion 14a may have a diameter slightly less than the diameter of the tobacco core 12 or in the alternative, the diameter may be the same and the end portion 14a provided with one or more longitudinal slots, not shown.

The arcuate exterior surface of center portion 14b is recessed slightly from the periphery of end portion 14a and functions as the impingement surface of the smoke as the latter flows as high-velocity jets through the filter in a manner to be hereafter described.

The downstream end portion Me of the core piece 14 has an outside diameter which is substantially the same as that of upstream end portion 14a. The periphery of end portion 14c is interrupted by a longitudinal slot 14d which cooperates with sleeve 15 to form a discharge port. In lieu of slot 14d, the end portion may be provided with a peripheral groove or an opening either of which being adapted to function as a discharge port. The end portions 140 and c of the core piece 14 provide support for the sleeve 15 which snugly encompasses the core piece 14.

The portion of sleeve 15 which is coextensive with the core piece center portion 14b cooperates therewith to form a substantially annular first passageway 18, see FIGS. 1 and 4. As will be noted in FIG. 3, the portion 18a. of the passageway formed by the arcuate exterior surface of the center portion 14b is shallow (e.g. theradial distance being approximately 0.015 inch), while, on the other hand, the remainder 18b of the passageway is relatively large. I

The portion of sleeve 15 forming the shallow passageway portion 180 is provided with a plurality of perforations 20 which may be arranged 'in one or a plurality of longitudinally extending rows. The number of perforations formed in the sleeve may vary from 10 to depending upon the size of the perforations which, in turn, may not exceed approximately 0.012 inch in diameter.

While the sleeve 15 may be formed from a web or film of thin (e.g. 0.001 inch thick) plastic, paper, or metallic material, there is no perceptible distortion of the sleeve while smoke is flowing through the perforations 20 because of the arched configuration of the sleeve in the vicinity of the perforations.

Encompassing sleeve 15 and in spaced, concentric relation therewith is the outer sleeve 16 which is formed of a thin smoke impervious material. In some constructions, the outer sleeve 16 may serve a dual function; (a) it cooperates with sleeve 15 to form an annular passageway 21 which communicates with passageway 18 only through perforations 20 and at the upstream end communicates directly with the tobacco rod 11, and (b) serves to overwrap the downstream end of the tobacco rod and affix the filter thereto. In other constructions, however, a separate outer wrapper, not shown, of tipping paper or the like in addition to sleeves 1S and 16 is provided for affixing the filter to the end of a tobacco rod.

It should be noted in either case that the smoke enters the passageway 21 at the upstream end thereof and fiows downstream therethrough. Because of the spacer piece 17, the smoke is blocked from continued flow through passageway 21 and thus, is diverted so as to flow radially inwardly through the sleeve perforations 20 into passageway 18. Due to the size and shape of the perforations, the smoke is separated into a plurality of high-velocity jets which impinge directly upon the adjacent arcuate surface of the core piece center portion 14b. Subsequent to the smoke jets striking the arcuate surface, it is split into two segments which are caused to flow along the arcuate surface portions disposed on either side of the point of jet impaction. Thus, by reason of this fact, greater utilization of the arcuate surface for deposition thereon of the smoke particles is effected and therefore the smoke particles will remain within the filter itself and not flow out the downstream end of the filter. By reason of the size differential between portions 18a and b of the passageway 18, the velocity of the smoke flow within passageway portion 18b is substantially reduced before it flows out the discharge port. It should be noted, that the discharge port for passageway portion 18b is angularly offset approximately 180 from the row, or rows, of perforations 20 thereby insuring that the smoke flow over substantially the whole arcuate surface of the core piece center portion 14b.

In various tests run with the improved filter embodying l6 perforations arranged in a single row and having an impact distance (the radial distance between the perforation and the arcuate exterior surface of the core piece center section) of 0.015 inch, it was found that the pressure drop across the filter after a length of the tobacco rod of approximately 58 mm. had been smoked did not exceed 3.6 inches of water and the efficiency of the wet tar removal varied from 55.6 percent to 57.2 percent. The length of the single row of perforations was approximately 7 mm. with the result that the overall length of the filter did not exceed l7 mm.

Where an improved filter was tested under similar conditions and two rows of eight perforations each were substituted for the single row in sleeve 15, it was found that the tar removal efficiency increased to 58.3 percent while the pressure drop across the filter did not exceed 3.20 inches of water.

Thus, with either construction, the efficiency of the tar removal was substantially greater than had been obtained with prior filters where the pressure drop did not exceed 3.6 inches of water after the rod had been smoked for at least 58 mm.

To facilitate assembly of the improved filter 10, an elongated rodlike member 22 is formed by extrusion and afterfonning, the latter being a well known and conventional technique. Member 22, as seen in FIG. 4, comprises a plurality of core pieces 14 integrally arranged in inverted end-to-end relation. While the member 22 is of rodlike form, it is snugly encompassed by a web 15' of perforated thin filmlike material. Web 15 eventually forms a plurality of sleeves 15 which comprise a part of the improved filters.

After web 15 has been applied, double-length spacer pieces encompass the web in the vicinity of the d0uble-length end portion 14' c formed in the member 22. If a separate outer wrapper of tipping paper is to be used to secure the filter to the tobacco rod, then a web of imperforate film, which will eventually form outer sleeve 16, is brought into encompassing relation with the rodlike member subsequent to the doublelength spacer pieces having been previously applied.

After the rodlike member has been encompassed by one or both of the sleeve-fonning webs, said member is cut along lines X-X, H6. 4, into two-up lengths and the tobacco rods affixed to opposite ends thereof in a conventional manner.

Following this step, the two-up segment with the tobacco rods attached is severed at its midlength along lines Y-Y to form two complete filter cigarettes.

Thus, it will be seen that an improved smoke filter has been provided which is of simple, inexpensive construction, is effective in removing liquid and/or solid particles from the flowing smoke, and is capable of being expeditiously assembled by automatic equipment.

I claim:

1. A smoke filter adapted to be affixed to an end of a tobacco rod, comprising a smoke impervious core piece having an enlarged upstream end portion for abutting the tobacco rod end, an elongated center portion having an exterior surface recessed from the peripheral surface of said end portion, and an enlarged downstream end portion, the latter having a longitudinally extending port fonned adjacent the periphery thereof; an inner sleeve snugly encompassing said core piece and cooperating with the center portion thereof to form an elongated substantially annular passageway communicating with the longitudinal port formed in the downstream end por' tion; said inner sleeve being provided with a plurality of perforations in registration with said annular passageway and closely adjacent to the exterior surface of said core piece center portion, the port in said core piece downstream end portion being angularly offset with respect to the perforations formed in said inner sleeve; and a second sleeve encompassing said inner sleeve and being spaced from the exterior thereof to form an elongated second annular passageway which circumvents the periphery of said core piece upstream end portion and is in communication with said first mentioned passageway only through said inner sleeve perforations, the upstream end of said second passageway being adapted to be in communication with the end of the tobacco rod whereby smoke passes from said second passageway through the sleeve perforations at a high velocity and impinges against the adjacent exterior of the core piece center portion, wherein the sleeve perforations are arranged in at least one longitudinally extending row.

2. The filter of claim 1 wherein said core piece center portion is substantially semicylindrical in configuration and the exterior surface of said center portion adjacent the sleeve perforations is curved.

3. The filter of claim 2 wherein the port formed in the core piece downstream end portion is substantially diametrically opposite said row of perforations.

4. The filter of claim 3 wherein the end portions of said core piece are of cylindrical configuration.

5. The filter of claim 3 including an annular spacer member disposed intermediate said sleeves and downstream of said perforations, said spacer member forming a smoke barrier.

6. A smoke filter adapted to be affixed to the downstream end of a tobacco smoking article comprising a smoke impervious core having an enlarged upstream end portion, an elongated center portion having an exterior surface recessed from the peripheral surface of said upstream end portion, and an enlarged downstream end portion, the latter having a longitudinally extending downstream smoke discharge port therein; an inner sleeve encompassing the upstream and downstream end portions and cooperating with the center portion to form a first passageway communicating with said port, said inner sleeve being provided with a longitudinally extending row of perforations in communication with said first passageway and in registry with said center portion, said row being angularly offset with respect to said port; and an outer sleeve encompassing said inner sleeve and defining therewith a second passageway which is in communication with said first passageway only through said perforations. 

2. The filter of claim 1 wherein said core piece center portion is substantially semicylindrical in configuration and the exterior surface of said center portion adjacent the sleeve perforations is curved.
 3. The filter of claim 2 wherein the port formed in the core piece downstream end portion is substantially diametrically opposite said row of perforations.
 4. The filter of claim 3 wherein the end portions of said core piece are of cylindrical configuration.
 5. The filter of cLaim 3 including an annular spacer member disposed intermediate said sleeves and downstream of said perforations, said spacer member forming a smoke barrier.
 6. A smoke filter adapted to be affixed to the downstream end of a tobacco smoking article comprising a smoke impervious core having an enlarged upstream end portion, an elongated center portion having an exterior surface recessed from the peripheral surface of said upstream end portion, and an enlarged downstream end portion, the latter having a longitudinally extending downstream smoke discharge port therein; an inner sleeve encompassing the upstream and downstream end portions and cooperating with the center portion to form a first passageway communicating with said port, said inner sleeve being provided with a longitudinally extending row of perforations in communication with said first passageway and in registry with said center portion, said row being angularly offset with respect to said port; and an outer sleeve encompassing said inner sleeve and defining therewith a second passageway which is in communication with said first passageway only through said perforations. 